1. Field of the Invention
The present invention relates to an automatic transmission for a vehicle. More particularly, the present invention relates to a planetary gear train of an automatic transmission for a vehicle which can improve power delivery performance and fuel economy.
2. Description of Related Art
Recently, rise of oil price accelerates enhancement of fuel economy.
Therefore, weight reduction and enhancement of fuel economy through downsizing have been developed in an engine field, and securing drivability and fuel economy through achieving multiple shift-speeds have been developed in an automatic transmission field.
However, if the number of shift-speeds in the automatic transmission increases, mountability, cost, weight and power delivery efficiency may be deteriorated due to increase of the number of components.
Therefore, it is very important to develop a planetary gear train having smaller number of components and securing better performance in order to enhance fuel economy through achieving multiple shift-speeds.
Currently, eight-speed and nine-speed automatic transmissions are found on the market. However, automatic transmissions achieving ten or more shift-speeds have been developed at a good pace.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.